1. Field of the Invention
The present invention relates to a power output apparatus, a method of controlling the same, and an automobile with the power output apparatus mounted thereon. More specifically the invention pertains to a power output apparatus that outputs power to a drive shaft, as well as to a method of controlling such a power output apparatus and an automobile with such a power output apparatus mounted thereon.
2. Description of the Prior Art
A proposed power output apparatus has an engine, a planetary gear mechanism that includes a carrier connected with a crankshaft of the engine and a ring gear connected with a drive shaft, which is mechanically linked with an axle, a first motor that outputs power to a sun gear of the planetary gear mechanism, a second motor that inputs and outputs power from and to the drive shaft, and a battery that transmits electric power to and from the first motor and the second motor (for example, see Patent Laid-Open Gazette No. 2000-197208). In response to a driver's accelerator-off action to require a braking force to the drive shaft, this known power output apparatus carries out regenerative control of the second motor corresponding to the requirement of the braking force, so as to charge the battery with regenerative energy, while outputting the required braking force to the drive shaft by regenerative braking control.
In the prior art power output apparatus, when the regenerative energy generated in the process of applying the required braking force to the drive shaft by regenerative braking control of the second motor exceeds an allowable charge limit of the battery, the second motor can output only the braking force corresponding to the electric power satisfying the charge limit of the battery. This may fail to output the required braking force to the drive shaft and deteriorate the drivability.